A polymer of a vinyl ether-type monomer can be produced usually by carrying out a polymerization reaction by a cationic polymerization method. Particularly, polymers of alkyl vinyl ethers are used for, for example, a tackiness agent, tackifier, adhesive, softener, paint, leather paint, fabric finishing compound, synthetic rubber modifier and the like.
A vinyl ether-based polymer is produced, in generally, by cationic polymerization of an alkyl vinyl ether using a Lewis acid polymerization catalyst (hereinafter, referred to as Lewis acid catalyst). In this cationic polymerization, usually, a compound having lone pair of electrons such as water, alcohol, acid, ether, halogen compound and the like is used as a co-catalyst. The degree of polymerization is controlled by the use amount of the polymerization catalyst and the co-catalyst, and the polymerization temperature, and the like. Specifically, there is a production method in which a desired alkyl vinyl ether is cation-polymerized in the presence of a co-catalyst such as an alcohol or the like, and a Lewis acid catalyst such as a boron trifluoride complex, anhydrous aluminum chloride or the like, then, the catalyst is deactivated to stop reacting, so, the vinyl ether polymer is obtained (for example, patent document 1 and the like).
However, in the case of carrying out cationic polymerization in the presence of the above-described Lewis acid-type catalyst, a low molecular weight polymer having a molecular weight of about several hundred, a so-called oligomer, is often obtained. In the case of production by a cationic polymerization method, a polymer having higher molecular weight is obtained generally by carrying out the reaction at lower temperature, however, it is known that, for obtaining a polymer having a molecular weight of several thousand or more, setting of the reaction condition to adjust the reaction temperature to 0° C. or lower, in some cases, causing a disadvantage for manufacturing in industrial level. It is difficult to obtain a high molecular weight polymer, and a molecular design in accordance with the purpose thereof is difficult as compared with an anionic polymerization method and a radical polymerization method, thus, its applicable use is limited.
As a method to get a high molecular weight polymer by a cationic polymerization, there is suggested a living cationic polymerization or the like. Patent document 2 discloses a method of carrying out living cationic polymerization of α-methylstyrene using a polymerization initiator composed of a specific organic halogen compound and a halogenated metal having Lewis acidity. Patent document 3 suggests a method of carrying out living cationic polymerization in the presence of a Lewis acid such as an organoaluminum complex, a tin complex and the like. However, in the living cationic polymerization method as described above, industrial manufacturing is difficult since a very highly active metal complex is usually used as the Lewis acid catalyst.
On the other hand, for obtaining a polymer having a radical reactive unsaturated group in a side chain, use is made of a method of introducing an unsaturated group into a polymer, by reacting a polymer having a reactive functional group in a side chain with an unsaturated compound having a substituent which is capable of reacting with this reactive side chain functional group. Typically mentioned are
(1) a method of introducing an unsaturated group by an acid epoxy reaction using an epoxy group-containing unsaturated compound such as glycidyl (meth)acrylate and the like,
(2) a method of introducing an unsaturated group by a urethane reaction using an unsaturated compound having an isocyanate group,
(3) a method of introducing an unsaturated group by an esterification reaction of a carboxylic acid and a hydroxyl group, or an amidation reaction of a carboxylic acid and an amine group,
and the like.
However, in the case of production of the above-described polymer by the above-described methods (1) to (3), a radical reactive unsaturated group is not introduced completely into a side chain, and a substituent having reactivity remains also after addition of a radical reactive unsaturated group, and depending on its use, there is a possibility of exerting a bad influence, and the number of processes increases, causing a problem in productivity, in some cases.
(Patent document 1) Japanese Patent Application Laid-Open (JP-A) No. 2001-122816
(Patent document 2) JP-A No. 5-310832
(Patent document 3) JP-A No. 2007-91977